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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #233847
Title: Evaluating Center Pivot Distribution Uniformity from Catch Can Tests

Author
item HENGGELER, JOE - University Of Missouri
item Vories, Earl

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 6/22/2009
Publication Date: 6/22/2009
Citation: Henggeler, J., Vories, E.D. 2009. Evaluating Center Pivot Distribution Uniformity from Catch Can Tests. In: Proceedings of the American Society of Agricultural and Biological Engineers Annual International Meeting. June 21-24, 2009, Reno, Nevada. ASABE Paper No. 096044. pp. 14.

Interpretive Summary: Center pivot irrigation is an important method for Missouri farmers and their crops. Irrigation system evaluations were performed on center pivots in Missouri to investigate the economic and performance characteristics of the systems and determine if improvements could be made. In addition to providing the farmers with useful information, suggestions were made concerning possible ways to improve testing methods in the future. The information gained from testing the performance of irrigation systems will help farmers to irrigate more efficiently, help pivot manufacturers by alerting them to the problems encountered during testing, and help everyone by ensuring that water and energy are not wasted by irrigation systems.

Technical Abstract: Center pivot irrigation is an important irrigation method in Missouri. However, only about half of the pivots in Missouri are the “typical”, full-circle, seven-span pivots. The other half are partial circles and/or have shorter or longer span lengths. Both items significantly impact the economics of pivot irrigation; however, while the percent of circle being irrigated affects unit area costs it does not affect uniformity. System evaluations were performed on 60 center pivots in Missouri. End guns irrigated an average of 16.8% of the area irrigated with pivots. The application rate under the end gun was, on average, 0.83 of the span, but in many instances was more (as much as double). An alternative procedure for describing uniformity was compared to the standard method. Since the catch can spacing was only 3 m (10 feet) it was reasoned that the adjacent down- and up-stream catch affected the crop around any particular catch can. As normally calculated, the state average CU was 79.6%; using the 3-can averaging method (CUadj) uniformity values increased to 83.8%. The CU value was only improved 1% by excluding the end gun catches in the calculations.